MUMBAI: At a workshop held at last month's BroadcastAsia 2004, techniques of protecting and restoring audio heritage material in the region were discussed by three experts.

These material exist with many broadcasters in the region in media such as old shellac discs, phonographic records, audio tapes and optical carriers, which have suffered damage due to ageing, poor storage conditions and bad handling.

The speakers discussed techniques of cleaning and restoring these disks, tapes and CDs. It is estimated that there are 300,000 cylinders, 10 million shellac discs, 4 million instantaneous discs and 25 million vinyl discs, and around 100 million hours of audio on tapes in existence.

The transfer of audio material from these formats is time consuming (estimates three times the duration of the material) and needs to be done at the best possible quality. CDs, though commonly believed to be robust, are not free from damage due to mishandling and poor storage conditions. One message that was conveyed at the session was that transfer technologies may improve over time, so Keep The Originals wherever possible.

In adtion there was a demonstration of electronic audio restoration using specialised equipment. The equipment used was Cedar from UK. It was impressive how well old audio material with a lot of noise, clicks and crackles was cleaned in real time. Specifically, an audio recording transferred from a broken record (but pasted together to recover audio) was cleaned removing the thumps that was produced when the stylus went over the join.

One message that came from this session was that material should be archived without being passed through any such digital restoration processes. Restoration technologies are constantly being improved and developed so that future restoration will need audio in the original state to achieve the best possible result. Digital restoration is recommended for restoring material for immediate use.